Electrical transformer having doublyoriented and random-oriented laminations



3,195,081 gRIENTED J. J. KUNES July 13, 1965 ELECTRICAL TRANSFORMER HAVING DOUBLY- AND RANDOM-ORIENTED LAMINATION Original Filed April 26. 1962 2 Sheets-Sheet 1 INVENTOR James J. Kunes j w y ATTORNEY WITNESSES WJW y 13, 1965 J. J. KUNES 3,195,081

ELECTRICAL TRANSFORMER HAVING DOUBLY-ORIENTED AND RANDOM-ORIENTED LAMINATIONS Original Filed April 26, 1962 2 Sheets-Sheet 2 Fig.5.

United States Patent 0 "co ELECTRICAL TRANSFORMER HAVING DOUBLE- ORIENTED AND RANDOM-GRIENTED LAME- NATIGNS James .I. Kunes, Sharpsville, Pa., assigncr to Westinghouse Electric Corporation, East Pittsburgh, Pa., 2 corporation of Pennsylvania Continuation of application Ser. No. 190,364, Apr. 26, 1962. This application Nov. 4, 1963, Ser. No. 321,314

3 Claims. (Cl. 336-5} This invent-ion relates in general to three phase inductive apparatus and more particularly to three phase transformer constructions which may efficiently utilize a round tank or casing.

This application is a continuation of the application filed April 26, 1962, Serial No. 190,364, now abandoned, and assigned to the same assignee as the present application.

In conventional three phase electrical inductive apparatus, such as transformers, a plurality of laminations or punchings is usually formed from magnetic sheet or strip material having a preferred direction of magnetic orientation or easier magnetization substantially parallel to its edges, or longitudinal dimension, such as cold rolled silicon steel. The laminations or punchings are then stacked or assembled together to form the different portions of the magnetic core structure required. Magnetic sheet or strip materials have now been developed which have more than one preferred direction of magnetic orientation and which have lower loss characteristics than the singly oriented magnetic material just described, particularly at smaller thicknesses such as three to four mils. For example, one type of doubly oriented magnetic strip material which has been developed has a first preferred direction of orientation substantially parallel to its edge or longitudinal dimension, and a second preferred direction of orientation substantially perpendicular to its edges or longitudinal dimension. One method of producing this doubly oriented material is described in detail in U.S. Patent 2,992,951 granted July 18, 1961, to R. G. Aspden.

The use of relatively thin doubly oriented magnetic materials in conventional magnetic core structures of the stacked type may not be practical due to the difficulties in handling larger laminations or punchings formed from such thin materials. It is therefore desirable to provide an improved three phase electrical transformer which utilizes a magnetic core constructed of a magnetic strip material which has more than one preferred direction of magnetic orientation and which lends itself to improved methods of manufacture and assembly.

It is, therefore, an object of this invention to provide a new and improved three phase electrical transformer. Another object of this invention is to provide a new and improved three phase transformer which has a magnetic core structure formed from a magnetic material having more than one preferred direction of magnetic orientation.

It is still another object of this invention to provide a three phase transformer that has a more rigid, lower cost magnetic core structure that allows a more compact overall transformer design.

A further object of this invention is to provide a three phase transformer that may be efiiciently contained in a round casing.

Briefly, the above cited objects are accomplished by winding the core for the three phase transformer out of a doubly oriented magnetic strip material to form an annular ring which is then pressed to form a substantially triangular yoke shape. A plurality of ring core members are also wound from the doubly oriented magnetic strip material which are assembled in end-to-end relation to form the desired length, and disposed in assembled rela- 3,195,981 Patented July 13, 1965 tionship :between two of the triangular yoke members to provide the magnetic core legs of the three phase inductive apparatus. The triangular shaped yoke members allow re core and coil structure to be efliciently contained in a round casing or tank, thus providing a transformer which requires less floor space and less cooling dielectric, as well as facilitating the manufacture, shipping, and installation of the transformer.

Further objects and advantages of the invention will become apparent as the following description proceeds and features of novelty which characterize the invention will be pointed out in particularity in the claims annexed to and forming a part of this specification,

For a better understanding of the invention, reference may be had to the accompanying drawings in which:

FIGURE 1 is a view of an annular yoke member made in accordance with my invention;

FIGURE 2 is a plan view of a three phase transformer utilizing a triangular shaped yoke member;

FIGURE 3 is a plan view of another triangular shaped yoke member for inductive apparatus;

FIGURE 4 is a plan view of another triangular shaped magnetic yoke member for inductive apparatus;

FIGURE 5 is a perspective, partially exploded view of a three phase transformer constructed according to the teachings of my invention;

FIGURE 6 is a plan view of still another magnetic core yoke member for inductive apparatus; and

FIGURE 7 is a plan view of a magnetic core yoke member comprising two concentric annular rings.

Referring now to FIGURE 1, an annular ring member 16 is shown. The member 10 is wound from a doubly oriented magnetic strip material. Examples of suitable types of magnetic material from which the laminations of the annular member 10 may be formed include siliconiron alloy containing from 1 to 7% silicon and aluminumiron alloy containing from 1 to- 10% aluminum. The strips of said alloys have grains whose crystal lattice structure comprises four cube edges perpendicular to the plane of the sheet, known as cube texture, which may be either doubly oriented or randomly oriented. A doubly oriented material has four cube edges of the cube lattice parallel to the rolling direction or edge of the sheet and four cube edges transverse thereto. In the randomly or singly oriented cube texture material, the grains may have eight cube edges randomly distributed parallel to the surface of the strip.

The annular or ring member 10 may be conveniently formed by winding a plurality of turns of magnetic strip material on a mandrel. A suitable electrical insulation would be provided between each turn of the strip material to thereby reduce eddy current losses in the magnetic core member. An example of such insulation is a coating of Carlite on at least one side of said strip material.

The laminated ring 16 may be pressed without buckling, to form a magnetic core yoke member of any geometric shape in which the length of the outside layer is equal to the length of the inside layer plus 21r times the thickness of the buildup. It can be shown that a yoke formed in the shape of any closed plane figure, such as a circle, rectangle, or triangle, will meet this requirement. The several turns of the annular member 10 may be held in fixed relation by any suitable bonding or adhesive material, such as a thermosetting epoxy resin. Examples of some of the geometric shapes possible are shown in FIGURES 2 through 7.

FIGURE 2 is a plan view of a three phase transformer 11 constructed in accordance with my invention. A perspective, partially exploded view of the transformer 11 shown in FIGURE 2 is illustrated in FIGURE 5, with the following description referring to both FIGURES 2 and 5. Basically, the transformer 11 comprises a magnetic core and coil structure 13, and a substantially round casing and cover 17 for enclosing the core and coil structure 13. The casing 15 may contain insulating means, such as liquid dielectric, for insulating and cooling the core and coil structure 13. Conventional high and low voltage bushing assemblies, 19 and Eli, may be mounted on the cover 17 and casing 15, respectively.

The core and coil structure 13 comprises upper and lower yoke members 12 and 14, respectively, leg members 16, 13 and 20, and high and low voltage of primary and secondary windings 23 and 25', respectively. For purposes of clarity, the high and low voltage windings are illustrated in phantom and, on one leg only in FIGURE 5. It is to be understood that the invention is not to be limited to the specific winding arrangements shown, as the arrangement illustrated is for purposes of example only.

The yoke members 12 and 14 are wound from a doubly oriented magnetic steel pressed to a substantially triangular shape. The triangular shape allows a round casing or tank 15 to be utilized which has a minimum diameter, thus conserving mounting space and fluid dielectric, as well as reducing manufacturing and shipping costs.

Each of the leg members 16, I8 and 2% comprises a plurality of stacked annular or toroidal magnetic core sections 27. Each of the core sections 27 includes a central opening therethrough and a radial gap extending axially therethrough. Each of the core sections includes a plurality of separate and independent laminations which are disposed in substantially concentric or nested relationship with respect to one another. The laminations are formed from a magnetic sheet or strip material having a coating of electrical insulation, such as Carlite, on at least one side thereof to reduce eddy current losses in said core sections. The magnetic strip material from which the laminations of the core sections are formed must have at least one preferred direction of magnetic orientation substantially perpendicular or transverse to the edges or longitudinal dimension of said strip material, and may also have a second preferred direction of magnetic orientation substantially parallel to the edges or longitudinal dimensions of said strip material. Means for holding the yoke and leg members in assembled relation, such as tie bolts 22, 24 and 26, extend through the yoke member 12, the plurality of core sections 27 making up the legs 16, 18 and 21D, and the yoke member E4, to thereby tie the yoke members 12 and 14 to the leg members 16, I8 and 20 and form complete magnetic loops. A 7

thin layer 28 of insulating material may be placed between the leg members 16, I8 and Ztl, and the yoke member 12 Similarly, leg members 16, 18 and 2d are insulated from yoke member 14 by electrical insulating layer 34. The plurality of core sections 15 may also be insulated from each other by a layer of insulating material 33. The tie bolts 22, 24 and 26 are insulated from the yoke members 12 and I4 and the leg members 16, I8 and 20, by placing an insulating washer 40 at eachend of the tie bolts 22, 24 and 26 and also placing insulating tubes (not shown) around the tie bolts 22, 24 and 26.

The yoke members shown in FIGURES 3 and 4 are modifications of the yoke members shown in FIGURES 2 and 5, and are formed by pressing an annular ring member similar to that shown in FIGURE 1 to the desired shape. Each of the substantially triangular shaped yoke members of FIGURES 3 or 4 has leg members 60, 62 and 6 fixed at the corners or apexes of the triangle formed by the yoke members 58 and 59. The leg members dd, 62, and M are indicated by the dot-dash line shown on FIGURES 3 and 4. The yoke members 58 and 59 and the leg members 6t), 62 and 64 are held in assembled relationship in any convenient manner; for example, by a tie bolt extending axially through the yoke member 58 and the leg members 60, 62 and 6d of FIGURE 3 or, bonding or banding the yoke member 59 and leg members 60, 62 and 64 in the configuration of FIGURE 4.

The yoke member shown in FIGURE 6 of the drawings is a modified embodiment of the invention. In the embodiment of FIGURE 6, a round laminated yoke as shown in FIGURE 1 would be pressed to form the triangular shape of FIGURE 6. The location of the leg members with respect to the yoke member may be as indicated by the dot-dash lines 66, 68 and '70. The yoke member 72 of FIGURE 6 and the leg members 66, 68 and '70 may be held in assembled relationship in any convenient mannor, for example, by tie bolts and insulating members similar to those shown in FIGURE 5.

FIGURE 7 is still another embodiment of the invention whereby the yoke member comprises two annular ring members Sill and 99. The two annular ring members 89 and 90 are assembled in concentric relationship, with the two annular members 86 and 9t) being wound so that the outside diameter of the inside annular ring is smaller than the inside diameter of the outside annular ring as, thus providing a slot or annular space 88 between the concentric rings 80 and 9th. The three leg members 32, 84; and 8-6 may be fastened in magnetic relationship with the rings 8% and 94) in any convenient manner; for example, by tie bolts and insulating washers through the slot 88 between the concentric rings 80 and 90, similar to the tie bolt arrangement illustrated in FIGURE 5.

The invention disclosed herein has many advantages. For example, the problem of utilizing the very thin, doubiy oriented magnetic steels has been solved by winding both the yoke and leg members. Thus, the handling of thin punched laminations is avoided and the manufacture of transformer cores facilitated by a Wound core construction that is faster and less expensive than stacking individual pre-punched laminations. This wound core construction has been made possible by utilizing doubly oriented silicon steel, which provides a path of easy magnetization through both the yoke and leg members in .the direction travelled by the magnetic flux. Further, the invention forms the yoke members in a triangular or round configuration, so that a three phase transformer may be efliciently disposed in a round tank or casing of minimum diameter. The triangular and round configuralions disclosed herein both illustrate how slots may conveniently be formed in the yoke members which provide openings for tie bolts to connect the yoke members and leg members in magnetic relation. Further, disposing a three phase transformer in a round tank of minimum diameter provides a transformer which is more compact, easier to handle, requires a minimum of cooling dielectric, and is, therefore, less costly to manufacture, less costly to ship, and easier and less costly to install.

While there have been shown and described what are at present considered to be the preferred embodiments of the invention, modifications thereto will readily occur to those skilled in the art. It is not desired, therefore,'that the invention be limited to the specific arrangements shown and described and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

I claim as my invention:

1. A three phase transformer comprising a magnetic core structure having two substantially triangular shaped yoke members and three leg members; said yoke members connecting said leg members in magnetic relation to form closed magnetic loops; each of said yoke and leg members being wound from doubly oriented magnetic strip material; means holding said yoke and leg members in assembled relation; high and low voltage windings disposed in inductive relation with each of said three leg members; a substantially round casing; said magnetic core structure, including said high and low voltage windings, being disposed in said casing; and insulating means disposed in said casing surrounding said magnetic core I leg members in magnetic relation to form closed magnetic loops; each of said yoke members comprising a plurality of laminations formed from a magnetic strip material; each of said yoke members having a substantially triangular shape with the length of the ouside lami nation equal to two 11' times the thickness of the buildup of laminations plus the length of the inside lamination; each of said yoke members having a triangular shaped central opening; a plurality of toroidal core sections formed from a magnetic strip material; each of said toroidal core sections having a radial opening extending axially therethrough; a plurality of said toroidal core sections stacked in end-to-end relationship with said radial openings substantially aligned to form said leg members; said magnetic strip material forming said toroidal core sections having a first preferred direction of orientation substantially parallel to the direction of rolling and a second preferred direction of orientation substantially perpendicular to the direction of rolling of said material; means extending through the radial openings of said leg members and the openings in said yoke members holding said yoke and leg members in assembled relation; primary and secondary windings disposed in inductive relation with each of said three leg members; a substantially round casing; said magnetic core structure, including said primary and secondary windings, being disposed in said casing; and insulating means disposed in said casing surrounding said magnetic core structure and said primary and secondary windings.

3. A three phase transformer comprising a magnetic core structure having two yoke members and three leg members; said yoke members connecting the ends of said leg members in magnetic relation to form closed magnetic loops; each of said yoke members having a triangular shape; each of said yoke members wound from a magnetic strip material; a plurality of toroidal core sections formed from a magnetic strip material; each of said toroidal core sections having a radial opening extending axially there- I through; a plurality of said toroidal core sections stacked in end-to-end relationship with said radial openings substantially aligned to form each of said leg members; said magnetic strip material forming said yoke members and said toroidal core sections having a first preferred direction of orientation substantially parallel to the direction of rolling and a second preferred direction of orientation substantially perpendicular to the direction of rolling of said strip material; means holding said yoke and leg members in assembled relation; primary and secondary windings disposed in inductive relation with each of said three leg members; a substantially round casing; said magnetic core structure, including said primary and second ary windings, being disposed in said casing; and liquid insulating means disposed in said casing surrounding said magnetic core structure and said primary and secondary windings.

4. A three phase transformer comprising a magnetic core structure having two yoke members and three leg members; said yoke members connecting the ends of said leg members in magnetic relation, forming closed magnetic loops; each of said yoke members comprising two substantially cylindrical members; said two cylindrical members concentrically disposed in spaced relation providing an annular opening in each of said first and second yoke members; a plurality of toroidal core sections formed from a magnetic strip material; each of said toroidal core sections having a radial opening extending axially therethrough; a plurality of said toroidal core sections stacked in end-to-end relation, with said radial openings substantially aligned to form each of said leg members; said mag netic strip material forming said yoke members and said toroidal core sections having a first preferred direction of orientation substantially parallel to the direction of rolling of said strip material and a second preferred direction of orientation substantially perpendicular to the direction of rolling of said strip material; means extending through the radial openings in said leg members and the annular openings in said yoke members holding said yoke and leg members in assembled relation; primary and secondary windings disposed in inductive relation with each of said three leg members; a substantially round casing; said magnetic core structure, including said primary and secondary windings, being disposed in said casing; and liquid dielectric disposed in said casing, surrounding said magnetic core structure and said primary and secondary windings.

5. A three phase magnetic core structure for electrical inductive apparatus comprising two yoke members and three leg members, said yoke members connecting said leg members in magnetic relation forming closed magnetic loops, each of said yoke and leg members being wound from a magnetic strip material having a preferred direction of magnetic orientation substantially perpendicular to the direction of rolling said magnetic strip material and a preferred direction of magnetic orientation substantially parallel to the direction of rolling, each of said yoke members being formed into a substantially triangular configuration, and means holding said leg and yoke members in assembled relation.

6. A three phase magnetic core structure for electrical apparatus comprising two yoke members and three leg members, said yoke members connecting the ends of said leg members in magnetic relation forming closed magnetic loops, each of said yoke members comprising a plurality of laminations formed from a magnetic strip material, each of said yoke members having a substantially triangular shape with the length of the outside lamination equal to 21.- times the thickness of the buildup of laminations plus the length of the inside lamination, each of said yoke members having a triangular shaped central opening, a plurality of toroidal core sections formed from a magnetic strip material, each of said toroidal core sections having a radial opening extending axially therethrough, a plurality of said toroidal core sections stacked in end-toend relationship with said radial openings substantially aligned to form said leg members, said magnetic strip material forming said toroidal core sections having a first preferred direction of orientation substantially parallel to the direction of rolling and a second preferred direction of orientation substantially perpendicular to the direction of rolling said material, and means extending through the radial openings in said leg members and the openings in said yoke members holding said yoke and leg members in assembled relation.

7. A three phase magnetic core structure for electrical apparatus comprising two yoke members and three leg members in magnetic relation forming closed magnetic loops, each of said yoke members having a triangular shape, each of said yoke members would from a magnetic strip material, a plurality of toroidal core sections formed from a magnetic strip material, each of said toroidal core sections having a radial opening extending axially therethrough, a plurality of said toroidal core sections stacked in end-to-end relationship with said radial openings substantially aligned to form each of said leg members, said magnetic strip material forming said yoke members and said toroidal core sections having a first preferred direction of orientation substantially parallel to the direction of rolling and a second preferred direction of orientation substantially perpendicular to the direction of rolling of said strip material, and means holding said yoke and leg members in assembled relationship.

8. A three phase magnetic core structure for electrical apparatus comprising two yoke members and three leg members, said yoke members connecting the ends of said leg members in magnetic relation forming closed magnetic loops, each of said yoke members comprising two substantially cylindrical members, said two cylindrical members concentrically disposed in spaced relation providing an annular opening in each of said first and second yoke members, a plurality of toroidal core sections formed from a magnetic strip material, each of said toroidal core sections having a radial opening extending axially there- 7 through, a plurality of said toroidal core sections stacked in end-to-end relation with said radial openings substantially aligned to form each of said leg members, said magnetic strip material forming said yoke members and said toroidal core sections having a first preferred direction of orientation substantially parallel to the direction of rolling of said strip material and a second preferred direction of orientation substantially perpendicular to the P 0 direction of rolling of said strip material, and means extending through the radial openings in said leg members and the annular openingsrin said yoke members holding said yoke and leg members in assembled relationship.

No references cited.

LARAMIE E. ASKIN, Primary Examiner. 

5. A THREE PHASE MAGNETIC CORE STRUCTURE FOR ELECTRICAL INDUCTIVE APPARATUS COMPRISING TWO YOKE MEMBERS AND THREE LEG MEMBERS, SAID YOKE MEMBERS CONNECTING SAID LEG MEMBERS IN MAGNETIC RELATION FORMING CLOSED MAGNETIC LOOPS, EACH OF SAID YOKE AND LEG MEMBERS BEING WOUND FROM A MAGNETIC STRIP MATERIAL HAVING A PREFERRED DIRECTION OF MAGNETIC ORIENTATION SUBSTANTIALLY PERPENDICULAR TO THE DIRECTION OF ROLLING SAID MAGNETIC STRIP MATERIAL AND A PREFERRED DIRECTION OF MAGNETIC ORIENTATION SUBSTANTIALLY PARALLEL TO THE DIRECTION OF ROLLING, EACH OF SAID YOKE MEMBERS BEING FORMED INTO A SUBSTANTIALLY TRIANGULAR CONFIGURATION, AND MEANS HOLDING SAID LEG AND YOKE MEMBERS IN ASSEMBLED RELATION. 